The present invention relates to methods and apparatus for controlling the flow of fluid in a well bore. More particularly, the invention provides a system for creating a flow path between adjacent screen jackets installed in a well bore.
In the prior art, for example, there are well bore operations which require the downhole placement of material, often via a fluid slurry, in the gap between the exterior of the screen jackets and the casing of the well bore. In order to ensure the reliability of the operation and placement of material in the gap, it is necessary to provide for the subsequent recovery of the fluid comprising the slurry. This may be accomplished by placing a port through the base pipe supporting the screen jacket. Fluid flows through the screen jackets and along the exterior of the base pipe to the port, where it flows into the inner bore of the base pipe for recovery from the well bore. The present invention provides a system that may be installed between adjacent screen jackets, thereafter providing a flow path between the adjacent screen jackets to the port while inhibiting flow to the inner bore of the base pipe.
Certain disadvantages have been identified with systems in the prior art. Typically, to obtain optimal results while performing various completion operations within the well bore, such as, for example, gravel packing, well stimulation, hole cleaning, or frac packing, it is desirous to provide some amount of fluid to return through the screen; from the area outside the screen jacket to the inner bore of the base pipe. In the prior art, a port is installed through the wall of the base pipe supporting the screen jacket. Preferably, the port is placed on the screen jacket positioned at the bottom of the production zone. The port allows fluid communication from the annular space outside the screen jackets to the inner bore of the base pipe. A wash pipe placed within the inner bore of the base pipe returns the fluid to the top of the well bore. Thus, a flow path is created from the annular space exterior the screen jackets through the screen jackets along the exterior surface of the base pipe. Fluid flows through the port and into the inner bore of the base pipe, where fluid is returned through the wash pipe to the top of the well bore.
It has been found that in some completion operations, such as gravel packing, for example, the area exterior of the screen jacket and the casing of the well bore (or walls of an open hole well) becomes filled with gravel. When a number of screen jackets are positioned above the port, the gravel placed in the well bore sequentially fills the gap between the top and bottom joints of adjacent screen jackets. Since there is typically a gap of about one to two feet between these joints, resistance is created to prevent or limit fluid flow between adjacent screen jackets due to material filling the gap between the base pipe and the casing (or walls of an open hole.) This affects the success and reliability of the treatment being performed in the well.
The prior art addresses this problem by either providing multiple ports uphole from the bottom port or increasing the pressure differential across the screen jackets. These solutions suffer from the drawbacks of being unreliable and/or increasing the complexity of well bore operations.
There therefore remains a need for a method and apparatus for controlling the flow of fluid during well completion operations by providing a flow path between adjacent screen jackets. The system should also isolate the inner bore of the base pipe from the flow of fluids to prevent contamination of the base pipe. The system should be reliable, safe, economical, and easy to install and operate within the well bore. The present invention satisfies these needs, among others.
The present invention provides an apparatus for coupling two adjacent screens to form an isolated fluid path therebetween.
The present invention further includes a method for coupling multiple screen assemblies. The method includes providing at least two screen assemblies mounted on a base pipe and coupling the assemblies to create an isolated fluid path between the screens.
In one aspect of the invention, an apparatus for controlling the flow of fluid in a well bore is provided. The apparatus includes an upper tubing section and a lower tubing section, each having a proximal end and a distal end. Each tubing section has a base pipe defining a bore, and each base pipe has an inner surface and an opposite outer surface extending between the proximal and distal ends of the tubing section. Each base pipe further includes an end portion, with the upper base pipe having the end portion at its distal end and the lower base pipe having the end portion at its proximal end. Each end portion defines at least one aperture communicating between the inner and outer surfaces of the base pipe. Each well section further includes a screen jacket positioned about the base pipe, the screen jacket and the outer surface of the base pipe defining an annular space therebetween. A sleeve is disposed between the upper and lower tubing sections to define an isolated flow path between the apertures, providing fluid communication between the annular space of the upper well section and the annular space of the lower well section.
Preferably, the end portion of each base pipe includes an end connector for engaging adjacent base pipe. In another preferred aspect, the sleeve sealingly engages the inner surface of the end connectors and isolates the bore of the base pipe from the fluid. In a further preferred aspect, each of the end connectors defines a recessed portion on its inner surface, and the sleeve engages the end connectors along the recessed portion so that the bore of the base pipe is substantially unobstructed by the sleeve. Preferably, the upper tubing section is engaged to the lower well section via a mechanical coupling.
In another aspect of the present invention, a method for controlling the flow of fluids within a well bore is provided. The method includes providing a base pipe having an outer surface and an inner bore and providing a first screen jacket and a second screen jacket positioned adjacent one another around the base pipe, each screen jacket defining an annular space between the outer surface of the base pipe and the screen jacket. A fluid flow path is created between the annular space defined by the first screen jacket and the annular space defined by the second screen jacket. Preferably, the inner bore of the base pipe is isolated from the fluid flow path.
In yet another aspect of the present invention, a method for controlling the flow of fluid between adjacent sections of tubing is provided. The method includes providing a first tubing section having a first base pipe defining a first bore and having an inner surface and an opposite outer surface, the first base pipe further including a first end portion at one end thereof, the fist end portion defining a first aperture communicating between the inner and outer surfaces. The first tubing section is assembled by placing a first screen jacket about the first base pipe, the first screen jacket and the outer surface of the first base pipe defining a first annular space. The method further includes providing a second tubing section having a second base pipe defining a second bore and having an inner surface and an opposite outer surface, the second base pipe further including a second end portion at one end thereof engaged in abutting relation with the first end portion, the second end portion defining a second aperture communicating between the inner and outer surfaces. The second tubing section includes a second screen jacket placed about the second base pipe, the second screen jacket and the outer surface of the second base pipe defining a second annular space. The method includes placing a sleeve in the first and second bores to create a flow path between the first annular space and the second annular space through the first and second apertures while isolating the first and second bores from fluid flow.
In still another aspect of the present invention, fluid may be returned to the top of the well through the base pipe port by the base pipe positioned at the bottom of the base pipe assembly. Fluid is returned through the port from the exterior of the screen jackets by flowing the fluid through the screen jackets into the annular space between the base pipe and the screen jacket. Fluid flows downward to the port through the annular spaces defined by the screen jackets positioned above the port.
According to a further aspect of the invention, there is provided an apparatus for controlling fluid flow in a well, the apparatus comprising: a primary screen; a primary base pipe within the primary screen, wherein a primary space is defined by the primary screen and the primary base pipe; at least one secondary screen; a secondary base pipe within the at least one secondary screen, wherein a secondary space is defined by the at least one secondary screen and the secondary base pipe; and a flow path between the primary space and the secondary space.
According to a further aspect of the invention, there is provided an apparatus for controlling fluid flow in a well, the apparatus comprising: a primary screen; a primary base pipe within the primary screen, wherein a primary space is defined by the primary screen and the primary base pipe; at least one secondary screen; a secondary base pipe within the at least one secondary screen, wherein a secondary space is defined by the at least one secondary screen and the secondary base pipe; and a flow path between the primary space and the secondary space, wherein the primary base pipe and the secondary base pipe are connected and a sleeve is positioned within and substantially concentric with the primary and secondary base pipes, whereby the flow path is defined by the primary and secondary base pipes and the sleeve, wherein the flow path further comprises at least one primary aperture in the primary base pipe and at least one secondary aperture in the secondary base pipe; a port in the primary base pipe between the primary space and an inner bore of the primary base pipe; and a valve which opens and closes the port in the primary base pipe.
According to still another aspect of the invention, there is provided a method for controlling fluid flow in a well, the method comprising: flowing fluid from an exterior of at least one secondary screen to a secondary space defined by the at least one secondary screen and a secondary base pipe; and conducting the fluid of the flowing from the secondary space to a primary space defined by a primary screen and a primary base pipe.
Further objects and advantages of the present invention will be apparent from the description of the preferred embodiment that follows.